of the lamprey and myxine. 267 
On the 5th of June, the ova were found to be of the full 
size, and a small transparent speck not before to be observed 
was seen in each; at this time the tubular structure had an 
increased breadth, and the duct going from it contained a 
ropy fluid, which when examined in the field of the micro- 
scope, was found to be composed of small globules in a 
transparent liquid. 
On the 9th of June, neither the ova nor the tubular struc- 
ture had undergone any change. 
On the 11th, the ova were of the same size, but the slightest 
force detached them from the ovarium, the tubular structure 
had increased still more in size, the fluid in the ducts was 
thicker, more ropy, and when water was added to it in the 
field of the microscope, it coagulated, and what was before 
made up of globules, had now the appearance of flakes. 
As these specimens had been kept two days, and had been 
carried 120 miles before they were examined, the appearance 
of the tubular part was seen under a disadvantage; but I was 
so fortunate on the 12th of June, as to receive from Sir Joseph 
Banks, the viscera of two lampreys caught in the river 
Thames, one of which had shed its ova, the other just ready to 
do so. In this last, the tubular structure from being in a more 
recent state was very distinct, and the difference in texture 
and appearance, between it and the black substance behind it, 
was more strongly marked. It is from this specimen that the 
annexed drawing was made, (PI. XIV.) in which the black part 
is seen to have a reticulated texture. As it runs up as high as 
the heart, and may be said to lie principally behind the peri- 
tonaeum, which is both the course and situation of the kidney 
in fishes, there can be no doubt that it performs the office of 
Mm2 
